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ext3: Update Kconfig description of EXT3_DEFAULTS_TO_ORDERED

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The old description for this configuration option was perhaps not
completely balanced in terms of describing the tradeoffs of using a
default of data=writeback vs. data=ordered.  Despite the fact that old
description very strongly recomended disabling this feature, all of
the major distributions have elected to preserve the existing 'legacy'
default, which is a strong hint that it perhaps wasn't telling the
whole story.

This revised description has been vetted by a number of ext3
developers as being better at informing the user about the tradeoffs
of enabling or disabling this configuration feature.

Cc: linux-ext4@vger.kernel.org
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Theodore Ts'o 2009-08-10 16:03:43 -04:00 committed by Jan Kara
parent f4b9a98868
commit 6d41807614
1 changed files with 15 additions and 13 deletions
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28
fs/ext3/Kconfig
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@ -29,23 +29,25 @@ config EXT3_FS
module will be called ext3. module will be called ext3.
config EXT3_DEFAULTS_TO_ORDERED config EXT3_DEFAULTS_TO_ORDERED
bool "Default to 'data=ordered' in ext3 (legacy option)" bool "Default to 'data=ordered' in ext3"
depends on EXT3_FS depends on EXT3_FS
help help
If a filesystem does not explicitly specify a data ordering The journal mode options for ext3 have different tradeoffs
mode, and the journal capability allowed it, ext3 used to between when data is guaranteed to be on disk and
historically default to 'data=ordered'. performance. The use of "data=writeback" can cause
unwritten data to appear in files after an system crash or
power failure, which can be a security issue. However,
"data=ordered" mode can also result in major performance
problems, including seconds-long delays before an fsync()
call returns. For details, see:
That was a rather unfortunate choice, because it leads to all http://ext4.wiki.kernel.org/index.php/Ext3_data_mode_tradeoffs
kinds of latency problems, and the 'data=writeback' mode is more
appropriate these days.
You should probably always answer 'n' here, and if you really If you have been historically happy with ext3's performance,
want to use 'data=ordered' mode, set it in the filesystem itself data=ordered mode will be a safe choice and you should
with 'tune2fs -o journal_data_ordered'. answer 'y' here. If you understand the reliability and data
privacy issues of data=writeback and are willing to make
But if you really want to enable the legacy default, you can do that trade off, answer 'n'.
so by answering 'y' to this question.
config EXT3_FS_XATTR config EXT3_FS_XATTR
bool "Ext3 extended attributes" bool "Ext3 extended attributes"